Lemurs of the genus Eulemur, including Eulemur macaco, are usually considered to be generalized, opportunistic frugivore-folivores, with a high degree of ecological flexibility. They are thus regarded as being able to adapt to a range of habitat types, and therefore less affected by the loss of primary forest habitat. In this study we assessed the suitability of altered forest habitat for the blue-eyed black lemur (Eulemur macaco flavifrons) on the Sahamalaza Peninsula (northwest Madagascar). Our aims were to identify structural vegetation characteristics that are important for the taxon, and to compare their availability in a primary and a secondary forest fragment. Home range size and habitat use of four groups of E. m. flavifrons, the availability of food resources and sleeping trees, as well as plant biodiversity and plant communities were investigated. The forest fragments harboring E. m. flavifrons groups differed in a number of structural variables. The density of food and resting trees was higher in primary forest. Home range size of blue-eyed black lemurs was larger in secondary forest. The lemurs used both habitat types differently. In the primary forest fragment the number of plant families and trees used for feeding or resting was higher. The results indicate that although E. m. flavifrons seems to be an edge-tolerant subspecies, the taxon nevertheless shows some degree of habitat specialization. The lower density of blue-eyed black lemurs in the secondary forest fragment indicates that this type of habitat is only of limited value to E. m. flavifrons.